Clinical and pathological characteristics of breast cancer with resected brain metastasis.

Abstract

1089 Background: Breast cancer brain metastasis (BCBM) has poor prognosis and limited therapeutic options. Studies have shown that BCBM may differ from their matched primary tumors in receptor subtypes and genomic characteristics. However, studies have been limited by the tissue availability of BCBM. Taking advantage of our institutional database of resected BCBM with matched primary breast samples, this study aimed to investigate the clinical and pathological characteristics of patients with resected BCBM. Methods: We performed retrospective chart review for all breast cancer patients who had resected BCBM samples at our institution over the last 20 years. Hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status of the primary breast and BCBM samples, location of BCBM, and extracranial metastases at time of BCBM diagnosis were categorized. Overall survival (OS) from time of BCBM diagnosis was calculated using the Kaplan-Meier method. Progression interval and receptor subtype switching from primary diagnosis to brain metastasis were computed and compared using Wilcoxon rank sum test and Fisher’s exact test, respectively. Results: Eighty-six patients were included in this study (median age at time of BCBM diagnosis 54.3 [range 28.3-84.0] years, median follow up 26.0 months). These included 47 HR+, 15 HER2+, 20 triple negative (TN), 4 unknown subtype breast samples, and 42 HR+, 18 HER2+, 17 TN and 9 unknown subtype brain samples. OS was significantly shorter in patients with TN compared to HR+ or HER2+ subtype, whether the TN status was in the primary breast tumor (median 20.5 vs 34.0 months, p = 0.04, thresholded at year 2) or in the brain metastasis (median 16.0 vs 34.0 months, p = 0.02, thresholded at year 2). No significant difference in OS was observed between HR+ and HER2+ groups. There was no significant difference in the progression interval from primary diagnosis to brain metastasis among receptor subtypes. From primary tumor to brain metastasis, receptor subtype switching occurred in 10 out of 73 patients (13.7%) for estrogen, 20 out of 70 (28.6%) for progesterone (PR), and 6 out of 72 (8.3%) for HER2. Receptor subtype switching did not significantly correlate with OS. Presence of extracranial metastases at time of BCBM diagnosis corresponded to significantly lower OS compared to no extracranial metastasis (16.5 vs 36.0 months, p = 0.01). No significant difference in OS was observed between patients with cerebral vs cerebellar brain metastases. Conclusions: These data indicate that patients with TN BCBM disease have the worst overall survival among all receptor subtypes. Metastases in extracranial sites at time of BCBM diagnosis significantly decreased survival. Location of the brain metastasis and receptor subtype switching from primary diagnosis to BCBM, which was relatively infrequent outside of the PR group, did not significantly correlate with OS in this limited data set.